1. Field of the Invention
The present invention relates to an image formation apparatus for forming a stable image by the electrostatic recording method wherein recording conditions of an image are controlled in accordance with surface conditions of a recording medium.
2. Description of the Prior Art
In image formation apparatus such as copying machines which record images in accordance with the electrostatic recording method, a potentiometer for measuring a surface potential is generally arranged near a recording medium, for example, near a photosensitive drum. A light color area and a dark color area are formed on the photosensitive drum to control various image formation conditions such as charge, exposure and development conditions in accordance with the measured results of the surface potential of the photosensitive drum whereby an optimum image is formed. However, in the conventional device of this type, potentials at the light color areas and the dark color areas are not measured in accordance with an original image, respectively. Therefore, even if the image formation conditions described above are controlled, the optimum image cannot be recorded, resulting in a low density image or a poor background appearence on the copying medium in accordance with a density difference of the background of various originals.